In general, crystalline polyolefins are relatively inexpensive and have excellent mechanical properties and, hence, they are being used for making various formed articles such as injection-molded articles, blow-molded articles, films, sheets and fibers. However, although the crystalline polyolefins possess excellent mechanical properties, they have the defect of being poor in transparency because of their crystalline nature and, for this reason, their applications are limited. For improving the poor transparency of the crystalline polyolefin, there have so far been used various nucleating agents. Among these, dibenzylidenesorbitol (hereinafter abbreviated as DBS) type compounds are relatively good in the effect of improving transparency, and are being widely used.
However, formed articles manufactured from crystalline polyolefin compositions containing such DBS-type compounds have a drawback that they emit the odor of benzaldehyde-type compounds which have been used as raw materials in synthesizing the DBS-type compounds and are contained therein as impurities or which have been generated through the decomposition of DBS-type compounds by acidic substances such as chlorine in molding or forming operations.
For the purpose of diminishing the odor-emitting properties of the composition prepared by incorporating a DBS-type compound in a crystalline polyolefin, there have been proposed a composition comprising the above composition and a decomposition inhibitor for DBS-type compounds (JP-A-58-21437), a composition comprising the above composition and a metal salt of a carboxylic acid (JP-A-60-147455), and a composition comprising the above composition and a non-aromatic organoamine compound (JP-A-62-4289). (The term "JP-A" as used herein means an "unexamined published Japanese patent application".) Further, there have also been proposed a composition comprising a crystalline polyolefin and a DBS-type compound surface-treated with stabilizers having chlorine-trapping properties which is at least one member selected from metal salts of fatty acids, metal salts of alkyllactic acids, and metal salts of lactic acid (JP-A-62-50355), a composition prepared by kneading said stabilizer beforehand with a crystalline polyolefin, and then incorporating a DBS-type compound in the mixture (JP-A-62-53360), and a composition which is a combination of the above two compositions (JP-A-62-138545).
The above-mentioned crystalline polyolefin compositions proposed in JP-A-58-21437, JP-A-60-147455, JP-A-62-4289, JP-A-62-50355, JP-A-62-53360 and JP-A-62-138545 in order to solve the transparency and odor problems, which compositions comprise crystalline polyolefins and, incorporated therein, DBS-type compounds and other various compounds, show considerably improved transparency and have also been improved to some extent in minimizing odors. However, the above compositions are still insufficient in these properties.